1. Field of the Invention
Embodiments of the present invention relate to a plasma processing system. More particularly, embodiments of the invention relate to a plasma processing chamber that induces a circulating flow of gases just prior to distributing the gases through a showerhead.
2. Background of the Related Art
Integrated circuits have evolved into complex devices that can include millions of components (e.g., transistors, capacitors, resistors, and the like) on a single chip. The evolution of chip designs continually requires faster circuitry and greater circuit density. The demands for greater circuit density necessitate a reduction in the dimensions of the integrated circuit components. The minimal dimensions of features of such devices are commonly referred to in the art as critical dimensions. The critical dimensions generally include the minimal widths of the features, such as lines, columns, openings, spaces between the lines, and the like.
As these critical dimensions shrink, process uniformity across the substrate becomes paramount to maintain high yields. One problem associated with a conventional plasma etch process used in the manufacture of integrated circuits is the non-uniformity of the etch rate across the substrate, which may be due, in part, to a lateral offset between the reactive species and the substrate being etched. One factor contributing to the tendency of the reactive species to be offset from the center of the substrate is inability for completely eliminate skew or azimuthal non-uniformity of gases provide to the processing chamber through a gas distribution plate. As gases may exit the gas distribution plate preferentially to one area of the chamber relative to another, the reactive (or other) species may become concentrated or starved in those areas, causing an offset, skew or azimuthal non-uniformity of processing results. This offset contributes to a loss of etch uniformity over the surface of the substrate which may significantly affect performance and increase the cost of fabricating integrated circuits.
Thus, as linewidths and critical dimensions continue to shrink, the need remains for a continued improvement in process uniformity in order to enable fabrication of next generation devices at a practical cost of manufacture. Therefore, there is a need in the art for an improved method and apparatus for etching material layers during the manufacture of integrated circuits.